The present and future of lighting is LED lighting. LED stands for light emitting diodes. LEDs have the inherent advantage of higher light output for a given amount of power consumption, a rated life of 100000 hours and no filaments to wear out or gases to leak. Besides, they are environment friendly and unlike fluorescent lighting, they do not have any mercury and are smaller in size. The world is switching to LED lighting because of the lower power consumption and better lighting qualities. Further, LED's are adjustable unlike fluorescents and can be electronically controlled, making them still more attractive as the lighting source for homes, commercial spaces and industries. From being used purely for indication purposes, LEDs, especially white LEDs, have now become light sources that are fast replacing incandescent, mercury, fluorescent, HPSV and metal halide technologies. One can retrofit LEDs into existing light fixtures and one can design new houses to have energy efficient LED lighting. Let's find out more about their behaviour and properties.
The LED light fixture or bulb incorporates the basic LED module or modules wired in series/parallel and the controlling circuitry. The complexity and design of the electronic circuitry plays a significant role in the quality of the LED and its light emission as well as life. Electronic controllers that have circuitry to automatically control current and voltage to safe limits translate to a longer bulb life. The quality of the basic LED in the fixture itself is also a determinant of the overall quality. A typical white LED works at 3.3V DC with maximum output at 3.7V but driving it at maximum voltage and current affects longevity. The chip and fabrication process also determine quality. Cheap, in the case of LEDs is not always better. A quality LED will have high quality LED along with quality electronic controller and heat dissipating heat sink.
It pays to consider all the aspects of LED lights before investing in them. Go for better quality and the investment is worth it. If you love lighting design, here's a home full of lights that you shouldn't miss : A home of thousand lights
The prime consideration for choosing LED lighting over incandescent, CFL or fluorescent tubes is their energy saving qualities. LEDs have the highest efficiency, they are able to convert electrical power to light energy with the least amount of heat produced per watt. Incandescent and halogen lamps are quite inefficient in that they produce maximum heat and only a small percentage of energy is converted to light. A 10 watt LED lamp has the same amount of lumen output as a 60W incandescent bulb. A power LED, be it a 1W or a 3W or a 30W LED, will produce heat as well, but it is significantly lower than that of an incandescent or halogen bulb. This means interiors will remain cooler and help in saving energy as well. Replacing all 60W incandescent lamps of fluorescent lamps with 20W LEDs will result in considerable savings in energy costs over a period of time.
LEDs are available in various power ratings. The smallest individual LED light is 1W followed by 3W, 5W and 10 Watt. Higher power LEDs are available in ratings of 20, 30, 60 and even 100 watts and above. However, if one looks carefully, a 3W LED module incorporate 3 1W chips inside. A 5W LED module integrates 5 of 1W LED chips. The advantage of LEDs is that they emit highly directional light whereas incandescent or CFL dissipate light in all directions. It only needs a 4W LED to provide the same brightness in a work area as a 25W lamp of a 10 watt lamp to provide the brightness of 60W lamp. An 18W LED lamp outputs 1300 lumens, equivalent to a 100W incandescent lamp. In simple terms one could say a 100 incandescent lamp is using about 80W to simply generate heat in comparison to LED power consumption. LEDs use about 90% less energy compared to incandescent light. LEDs can be dimmed with an electronic controller, making them even more energy efficient. A quality LED may have typical efficiency of 40 lumens per watt. Recent innovations by leading manufacturers have resulted in LEDs with higher 300 lumens per watt figure.
LEDs have another advantage over incandescent, CFL, fluorescent tubes, sodium vapor and mercury lamps. All these lamps emit light in all directions and a major amount of the light output is wasted. LEDs emit directional light and when used with appropriate fixtures, the entire amount of light from an LED can be directed to specific work areas. LEDs for lighting have a wide dispersion angle up to 120-160 degrees instead of the 360 degree pattern of the other lamps. This means more light quantity is available in a defined area and a lower power LED lamp can be used to provide more than sufficient amount of light. Most homes and work places do not require light to be spread in all directions and use a fixture to direct light. LEDs, by providing a beam of light in a specific direction, obviate the need for fixtures or require only low cost fixtures.
The colour temperature of light is measured in Kelvins. Incandescent light has a colour temperature of about 3400 deg. K, which is yellowish. Fluorescent tubes, depending on the coating inside, emit light with colour temperatures ranging from golden yellow (3400 deg. K) to 6500 deg K (cool daylight). Researches show that various colour temperatures have various effects on human beings. LEDs are typically available in colour temperatures from 3400 deg. K to 6000 deg. K. In living areas, dining areas and in kitchens, it has been found that a warmer colour temperature of about 4000 deg. K makes for a cosy atmosphere more conducive to interaction. Workplaces in offices, homes and in factories would do better with a colder colour temperature of about 6000 deg. K that promotes efficiency and productivity. 5500 K is the colour temperature of sunlight. LEDs are available in this colour temperature range and are best for homes that suffer from lack of natural lighting. Buy in bulk and save. If you are more choosy, select warmer LEDs for living areas and for bedrooms and cooler LEDs for study and workplaces in your home.
Most manufacturers specify that an LED has a life of 100000 hours. However, this is at the rated temperature of 25 deg. C. Derating applied for rise in temperature curtails the life of most LEDs to around 50000 hours. Another significant factor affecting durability is the working voltage and current. LEDs are current sensitive. If current exceeds the rated safe current, then LED life reduces significantly and it may even burn out. Exceeding voltage also derates life. Another significant factor affecting LED bulbs and fixtures is the components used in the electronic controller and the design of the controller itself. Components may blow and this will render an LED bulb unusable even if the LEDs are fully functional. LED lamps used with dimmers, operating them at lower than their rated power; will result in significantly enhanced durability of the lamp. Another factor is the manufacturer as top quality manufacturers offer better quality LEDS with better durability. The lighting in the living room shown above is the work of Eden Verandas, garden and landscape supplies from Hampshire, UK.